I'm wondering what happens when a water heater fails due to old age? I see corrosion on my inlet and outlet pipes like I'd mentioned in a post a while back, and I'm concerned about this. Plus the water heater's from 1985. It's functioning fine except for crackling sounds when it's operational, but that's probably because I haven't drained it since I bought the place a year ago.

So, what happens when a water heater fails due to old age? If it's nothing destructive and it just means no hot water until it's replaced I'm willing to just stick with my current water heater.

Also, what's the proper way to clean out the water heater? Should I drain all of the water? Or do I drain a small amount at a time until I don't see any sediment? I've never done this before and I don't know who to ask.

When the water heater "goes", it can develope a small leak from the tank, a large leak from the tank, the inner liner of the tank can fail causing rusty water to be delivered to the fixtures or the gas valve/thermostat could fail. If the thermostat fails, it's a judgement call as whether the heater is worth repairing or replacing. When flushing out the heater, you only need to drain until clear water comes out.

Electrics usually are considered "bad" when there is so much junk in them you can't get the elements out, or when the sediment is up to the bottom element, or when the tank begins leaking.

Gas normally let you know by leaking. Most often, near the bottom and quite often with a tank rupture that causes flooding in the home.

This is why devices like the FloodMaster are getting easier to sell customers. If water hits the sensor for any reason, the Homeowner is notified by alarm and the problem can be handled without water damage.

Most people at least know somone who has been displaced by an event like this and would prefer to avoid it, knowing that it is not uncommon.

Another failure is from the anode rod going. They wear more at the top where air gathers during the release of it by heating the water. This is the point that will get eaten down to the bare steel rod that the magnesium is on and once the rod is exposed the bad stuff attacks the tank, normally at the top and will cause leaking there, instead of at the bottom. If the heater (and house)is well grounded this takes a long time.

After 20 years the stuff that is making the noise is well adhered to the tank and flushing it is not going to remove it. The majority of heaters start with a small amount of water around them when they fail. Catastrophic failures are not the norm and are usually caused by some unique problem in the house or heater.

Not the norm is true, but almost everyone I know, at least knows someone who's tank water heater has leaked or ruptured and caused water damage to the home.

It does not have to be the norm to be a big deal when you think about just how many water heaters are out there. They number into the bazillions!

I like your question as it doesn't have a single answer. Because of so many different manufacters, styles, water conditions and enviroments, it would take our best computers to issue you odds at failure of a water heater. But this we know, water heaters fail. An when they fail, it can be slow and painfull. It can also be fast and painfull. To reduce the odds of failure, determine the make and model of YOUR water heater. Call that manufacturer with the model and serial number. Let them know of the water conditions and how much annual serving has been done on the water heater since it was installed. Base on that information will tell you how much longer it will last.
Did I mention the affects earthquakes have on water heaters?
Pray that you are standing by your water heater when it fails and that you have an oversize floor drain that can handle the 40-50 gallons of water when your heater dumps. Best Wishes!

The only real "ruptures" I can remember, off hand, are with State's Duron tanks. Many had the threads on the elements rust off and then it blew out, and one, probably a grounding issue since it never occurred again after I shorted the hot and cold together, looked like someone had used a can opener on the top of the tank between the hot and cold pipes.

I do not care how much information you give the manufacturer, no one can tell you how long it will last.

If the water heater is pushing 20 years then I hope it has a safety pan under it. If not consider installing one. Be sure to install safety pan when/if you install a new water heater. GOOD LUCK

How would they install one under the existing heater without taking it out. And if they are going to do that, they might as well install a new heater rather than put the old one badk.